Custom Chromo: First Yeast Chromosome Built From Scratch : Shots - Health NewsIt's not about making designer beer. Johns Hopkins scientists and undergrads stitched together strands of yeast DNA as a step in exploring the essential genetics of various species: What makes us us?

Scientists have built a customized chromosome from scratch. It is a yeast chromosome. The yeast is a humble organism but this is a very big deal in the rapidly growing field of synthetic biology, where organisms can be tailored for industrial use. In this case, the near-term goal is to understand the genetics of yeast and eventually the genetics of us.

NPR's Richard Harris tells us the research involved the labor of hundreds of undergraduate students.

RICHARD HARRIS, BYLINE: Yeast have about 6,000 genes packed in 16 tidy bundles, chromosomes. Each chromosome is an enormous molecule. But Jef Boeke remembers the day, about 15 years ago, when a prominent geneticist named Ron Davis got up at a meeting and declared that someday someone would build a yeast chromosome from scratch.

JEF BOEKE: When Ron suggested that someday someone would make a yeast chromosome, I remember saying to myself: Why on Earth would anyone do that?

HARRIS: Boeke was a geneticist at Johns Hopkins.

BOEKE: Fast forward 10 years later, I bump into my colleague Chandra in the coffee shop, and we were talking about synthesizing this and synthesizing that and at one point, I said to him, well, you know, we could make a yeast chromosome. The technology's all there. And he looked at me incredulous and he said, really? He said, we've got to do it! We've got to do it! And practically was jumping up and down with excitement.

HARRIS: At first, Boeke says he tried to buy some of the DNA strands they wanted to use from a company. But the first small batch took nearly a year to arrive.

BOEKE: I realized that I would be dead long before the project could ever be completed. So it suddenly hit me that there were all these students on the undergraduate campus who would be dying for a great research opportunity.

HARRIS: So Boeke and his colleagues put together a class called Build-A-Genome, and got undergraduates to do the painstaking labor of constructing long strings of DNA, segments of their yeast chromosome. And they now report success in Science magazine. They've built yeast chromosome No. 3 from scratch. To make it useful for research, they've deleted some parts of the DNA that they believe are not essential.

BOEKE: And then we add a number of bells and whistles to the chromosome that we think will make for a more interesting version that we can play evolutionary games with in the laboratory.

HARRIS: They're interested in going after big questions, such as what is it in the DNA that keeps one species separate from the next? Of course, this deep manipulation of DNA also raises ethical questions about everything from patenting life-forms, to the potential misuse of biotechnology for weapons or other nefarious purposes. So part of the class involved an ethics discussion, led by Debra Mathews at Hopkins.

DEBRA MATHEWS: It's not just this particular project, right? They're learning techniques that are transferable to many other organisms and, because you have this fantastic power to modify DNA, that it comes with responsibilities.

HARRIS: Stanford Medical School geneticist Ron Davis, the guy who suggested that someone would eventually do this, says he's impressed. He says you might be tempted to dismiss this as a stunt.

RONALD DAVIS: But when it's with yeast, it's not a stunt. It's a milestone event in my opinion.

HARRIS: If scientists can build all 16 yeast chromosomes from scratch, they'd have an entire set of yeast genes to tinker with at will. Davis says that would be a big advance for understanding how genes work, in yeast and by extension in humans.

DAVIS: You can look at a car and you think you understand a car, but if you really understand a car you should be able to build one.

HARRIS: As for Jef Boeke, he's hot on the trail of other chromosomes from his new outpost at the NYU Medical Center. He says the project has taken on a lot of momentum and labs around the world are currently working on 15 out of the 16 yeast chromosomes.

BOEKE: If there's any millionaire out there who would like chromosome 16 named after them, tell them to get in touch.

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